We propose to analyze the molecular basis for the regulated expression of two important gene sets in higher plants, the heat shock gene family and the cell wall hydroxyproline rich glycoprotein (HPRGP) gene. Both gene sets are highly inducible, at both the mRNA and protein levels, by important physiological stresses, namely heat shock and ethylene. Furthermore, we now have evidence which indicates that the HPRGP gene is independently regulated by both ethylene and heat shock, and there is reason to believe that subsets of the heat shock gene family will exhibit independent developmental regulation as well in our system, carrot. Thus, we have in these two gene sets the potential to study multiple regulatory regions governing single structural genes which may serve vital physiological roles both during normal development and in response to stress. We propose to delimit those DNA sequences of each gene set responsible for these forms of regulation by modifying and/or deleting potentially important regions and assaying their ability to function in a regulated fashion after transformation back into carrot cells. This type of detailed molecular analysis is an essential step toward utilizing these highly inducible "promoter" sequences to direct the controlled expression of potentially useful agronomic traits, and represents a fundamental beginning toward crop improvement through biotechnology.